This application claims benefit under 35 U.S.C. 371 to international application No. PCT/NL00/00164, filed on Mar. 10, 2000.
The present invention relates to an arrangement for transferring an ovum from a follicle with a combined aspiration and flushing technique and in accordance with the introductory part of claim 1.
An arrangement of this type is known from Australian patent AU-B-68184/87. In this known arrangement the two tubes, that is to say, the inner tube and the outer tube, are made of stainless steel. The inner tube has an outside diameter that accurately fits in the inside diameter of the outer tube and is coaxially located inside the outer tube. For creating a flushing lumen between the inner tube and the outer tube, the inner tube is provided with an inward deformation running in longitudinal direction of the tube, seen in cross-sectional view of the tube, not exceeding 120xc2x0. The consequence of this local inward deformation is that the wall of the inner tube, seen in cross-sectional view of the tube, has an inwardly directed convex portion that connects to the remaining portion of the wall of the inner tube via rounded concave portions. In this way the lumen of the inner tube is reduced while at the same time a lumen is developed at the position of the inward deformation between the inner tube and the outer tube. The latter lumen is used as a flushing lumen for supplying the flushing fluid. The lumen, which is bounded by the inside wall of the inner tube is used as the ovum pick-up lumen. For a more detailed description and drawings of an arrangement according to this known state of the art, reference be made to Australian patent document AU-B-68184/87 mentioned above, whose contents, insofar as of importance for the present application, is deemed to be included herein by reference.
A similar arrangement is known from DE-A-3522782. In this arrangement however, the function of the two lumens is reversed.
The above-described known construction of an arrangement for transferring an ovum from a follicle has several disadvantages. The inner tube is to fit accurately within the outer tube, which necessitates accurate tolerances, both as regards the inside diameter of the outer tube and the outside diameter of the inner tube. Adhering to accurate tolerances always has a disadvantageous effect on the cost price. Another disadvantage is that the ovum pick-up lumen does not have a round cross section since the wall of the inner tube has a local inward deformation. Finally, when the point of the needle is made, for example by means of grinding, material is to be removed both from the outer tube and from the inner tube. In addition, the grinding is to be carried out with the flushing lumen in a certain orientation in order to guarantee that with the finished product the flushing lumen is in the right position relative to the point of the double lumen needle.
It is an object of the invention to improve an arrangement of the type defined in the opening paragraph so that the above disadvantages are avoided and, in addition, advantages are provided which will be discussed hereinafter. For this purpose, the invention is characterized by the features stated in the characterizing part of claim 1.
The arrangement according to the invention has a number of characteristic advantages. The inner tube does not accurately fit in the outer tube, so that no accurate tolerances are necessary either for the outer tube or for the inner tube. The inner tube is made of a flexible material, so that the dimensions of the ovum pick-up lumen when an ovum passes can at least slightly adapt to the dimensions of the ovum. The flushing lumen is bounded by the inside wall of the inner tube, while the ovum lumen is bounded by the space between the outside wall of the inner tube and the inner wall of the outside tube. This implies that the flushing fluid used is in contact with metal only along the path from the distal end of the needle body to the outlet at the end remote from the distal needle end. This is deemed favourable. Metals are soluble in water only to a very small extent, it is true, but, nevertheless, an ovum should as much as possible be avoided contacting metals or fluids that have been in contact with metals. According to the state of the art, plastics can be manufactured having a composition that may be deemed utterly man-friendly.
The advantages of the invention turn out to be not only of a manufacturing nature, but also of importance for as good a protection of the ovum against possible damaging mechanical and chemical ambient influences during the transfer from the follicle to a receptacle, such as a glass test tube or the like to be connected to the outlet. Therefore, preferably an embodiment of the invention is utilized that is characterized in claim 2.
Claim 3 relates to a practical embodiment of the invention. In this embodiment the inner tube has such outside shape that the latter can be contiguous to the inside wall of the outer tube and thus over this part of the circumference has an outside diameter that is at least substantially equal to the inside diameter of the outer wall. The remaining, second part of the outside wall of the inner tube can elastically be deformed in the direction of the first portion. It will then be favourable when, during the passage of an ovum, the second part of the inner tube is deformed as far as possible in the direction of the first part. Alternatively, the flushing lumen should not be closed off completely when in that case too it is deemed desirable to have supply of flushing fluid.
Claim 4 relates to an embodiment of the arrangement according to the invention in which the inner tube is connected at least at the distal end by gluing it to the inside wall of the outer tube. In the description of this embodiment with reference to the drawings it will further appear that this embodiment can be designed so that during the grinding process of the point to the needle body at the distal end of the needle the inner tube need not be taken into account at all and the material of the inner tube need not be ground either.
For connecting the inner tube to the flushing inlet for supplying the flushing medium, the embodiment according to claim 5 is of importance. This embodiment is possible due to the flexibility of the inner tube as a result of which it is possible to feed-in the inner tube in a bend through an opening in the outer tube.